ITGB2 promotes HIF-1α/GLUT1 mediated glucose metabolic reprogramming in renal tubular epithelial cells to aggravate the progression of diabetic kidney disease

Abstract

Diabetic kidney disease (DKD) is characterized by tubular metabolic remodeling, inflammation, and profibrotic injury. However, whether integrin β2 (ITGB2) links high-glucose (HG) stress to hypoxia-inducible factor-1α (HIF-1α)/glucose transporter 1 (GLUT1)-dependent metabolic reprogramming in renal tubular epithelial cells remains unclear. This study investigated the role and underlying mechanism of the ITGB2/HIF-1α/GLUT1 axis in HG-induced tubular injury. ITGB2 expression was first examined in the publicly available human renal transcriptomic dataset GSE30529. HK-2 cells were cultured under normal-glucose, HG, or mannitol osmotic-control conditions. ITGB2 was silenced or overexpressed, and HIF1A or SLC2A1/GLUT1 was knocked down by siRNA. Protein expression, HIF-1α nuclear accumulation, and HIF-1α protein stability were assessed by western blotting, subcellular fractionation, and cycloheximide-chase assays. Metabolic remodeling was evaluated by 2-NBDG uptake, lactate production, extracellular acidification rate (ECAR), oxygen consumption rate (OCR), and ATP content. Tubular injury, inflammatory, and EMT-like/profibrotic phenotypes were assessed by ELISA and RT-qPCR. Dual-luciferase reporter and chromatin immunoprecipitation assays were performed to evaluate HIF-1α-mediated transcriptional regulation of GLUT1. ITGB2 expression was increased in the tubulointerstitial compartment of human diabetic kidneys in GSE30529. In HK-2 cells, HG increased ITGB2, HIF-1α, and GLUT1 expression, accompanied by increased glucose uptake, lactate production, ECAR, and ATP content and reduced OCR, together with enhanced tubular injury, inflammatory, and EMT-like/profibrotic responses. ITGB2 knockdown reduced HIF-1α/GLUT1 expression and nuclear HIF-1α accumulation and accelerated HIF-1α protein decay, suggesting that ITGB2 contributes to HIF-1α protein stability. HIF-1α directly bound to and transcriptionally activated the GLUT1 promoter. ITGB2 overexpression further enhanced metabolic reprogramming and pathological phenotypes, whereas HIF1A or SLC2A1 silencing markedly attenuated these effects. ITGB2 promotes HIF-1α/GLUT1-dependent metabolic reprogramming and contributes to tubular injury, inflammatory, and EMT-like/profibrotic responses in HG-treated HK-2 cells. These findings support a role for the ITGB2/HIF-1α/GLUT1 signaling axis in coordinating metabolic and pathological responses under HG conditions.